What should we watch out for when the cooling tower and pump are at the lowest point of the system(1)

PS1:When the cooling tower and cooling water pump are at the lowest point at the same time:

1. Install an exhaust valve at the highest point of the water system;

2. Install a check valve at the horizontal position of the water outlet of the pump to avoid water backflow in the cooling system;

3. The pump head must be greater than [(the difference between the highest and lowest points of the cooling system) + system pressure];

4. Install the electric two-way valve at the horizontal position of the water inlet of the cooling tower. When the unit is stopped, the electric two-way valve is closed to avoid water backflow in the system.